1Line 11x7-inch (2-quart) glass baking dish or 9-inch square pan with foil, extending foil 1 inch over 2 opposite sides of pan; grease foil with butter.
2In 3-quart heavy saucepan, mix sugar, milk, butter, marshmallows and salt. Heat to boiling over medium heat, stirring constantly. Boil 5 minutes, stirring constantly. Reduce heat to low. Stir in chocolate chips and vanilla until mixture can be stirred smooth. Pour into pan. Immediately sprinkle with nonpareils. Cool completely, about 1 hour.
3Use foil to lift fudge out of pan. With 2-inch Christmas tree-shaped cookie cutter, cut fudge. Insert 1 stick into bottom of each cutout. In small microwavable bowl, microwave vanilla chips and shortening on Medium (50%) 30 to 45 seconds; stir until chips can be stirred smooth. Drizzle over plain side of fudge. Let stand until set.